Definition. A metric space is a set X together with a function d (called a metric or distance function) which assigns a real number d (x, y) to every pair x, y X satisfying the properties (or axioms): 1  d (x, y) 0 and d (x, y) = 0 x = y, 2  d (x, y) = d (y, x),
Here are some facts and guidelines about formaldehyde in plywood and OSB that can help you when building a chicken coop: 1  Formaldehyde is used in the binders and resins of some manufactured wood products. 2  Offgassing can be an issue with products containing urea-formaldehyde (UF) resins.
However, OSB is generally considered less resistant to water (it swells in thickness when exposed to moisture) and some people prefer plywood for roofs and subfloors. The Miami-Dade County Board of County Commissioners banned OSB for use as roof sheathing after Hurricane Andrew destroyed thousands of homes in 1992.s OSB is cheaper than plywood and has the strength and durability of plywood it is becoming more widely used than plywood. OSB was introduced in the 1970s and steadily gained market share from plywood, surpassing plywood in production in 2000. Today OSB has 70-75% market share and plywood has about 25% share.